This fight literally anything is possible other than a KO from Diaz

Diaz by tko
Diaz by decision
Paul by ko
Paul by tko
Paul by decision
Paul by doctor stoppage

Most likely is probably Paul lands some decent shots but Diaz won't go away and Paul starts tiring in the later rounds and Diaz comes on. Depending on how fast Diaz comes on it will either be a decision loss or win for him

If Diaz starts tiring him immediately and landing his high volume pressure shots he could tko him. But he's gotta be in his face really early to exhaust him enough for a later tko